text: /****************************************************************************************
  *  @author: kzvd4729                                         created: Apr/03/2018 23:00                        
  *  solution_verdict: Wrong answer on hack 1                  language: GNU C++17                               
  *  run_time: 46 ms                                           memory_used: 3300 KB                              
  *  problem: https://codeforces.com/contest/959/problem/C
  ****************************************************************************************/
  #include<bits/stdc++.h>
  #define long long long
  using namespace std;
  int n,cnt,nn;
  int main()
  {
    scanf("%d",&n);
    if(n<8)
    {
      n--;
      printf("-1\n");
      cnt=1;
      while(n--)
      {
        printf("%d %d\n",cnt,cnt+1);
        cnt++;
      }
    }
    else
    {
      nn=n;
      nn--;
      printf("1 2\n");
      printf("1 3\n");
      printf("2 4\n");
      printf("2 5\n");
      printf("3 6\n");
      printf("4 7\n");
      printf("4 8\n");
      nn-=7;
      cnt=8;
      while(nn--)
      {
        printf("%d %d\n",4,++cnt);
      }
      n--;
      cnt=1;
      while(n--)
      {
        printf("%d %d\n",cnt,cnt+1);
        cnt++;
      }
    }
    return 0;
  }